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Old 11-13-2008, 07:23 AM   #41 (permalink)
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Volvo - '00 Volvo V70 XC AWD SE
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Originally Posted by MazdaMatt View Post
physics aside... I also am looking for ways to more efficiently drive my big (huge) diesel truck. It is less aerodynamic than a brick and weighs between 5000 and 8000 pounds depending on the load.
23L/100km...what is what, about 6 gals per 63 miles? 10-11 mpg?

I have an 8,000 lbs diesel van and I know how you feel. I get 16-17 highway, but could get more if I didn't use 100% biodiesel. I think there are a few things you can do easily:

1. Inertia management: This means never using your brakes, not fully stopping at stops signs, and taking the best line in any corner. Keep as much velocity as you can at all times so you don't have to regain it with the throttle. It's funny that your truck won't coast well. My heavy van coasts forever. Throw it in neutral. On the highway I accelerate gently to over the limit going downhill and then use minimum throttle going up the next hill, letting the van gradually slow down to under the speed limit.

2. Use highway tires and not agrressive tread tires. My mileage dropped by 4 mpg when I went from highway treads to M&S. Grrr.

3. Don't accelerate too slowly. Get up to speed fairly quickly and then back off the throttle. Try to get in high gear as soon as you can. Having said that, 2,900 rpm shift points seem WAY high for a diesel.

4. Although this doesn't improve mileage, it does save gas - use a GPS to plot your routes. Plot both the shortest route and if you have multiple stops let it plot the most efficient order of the stops. GPS is the most underused gas-saving tool on the planet IMO. If you save just one mile out of ten that's a ten perent improvement.

5. Change your oil to a lower viscosity one. I use 0-40W in my diesel year round and I do notice a difference engine friction and starting.

6. Make sure your radiator fan clutch isn't frozen. That will cause huge mileage losses.

You may have transmission gear ratios set up for city driving and not for highway use. That would make sense with the Hostess truck and would explain those high rpms. Chaging the final drive ratio is not that hard to do and could help a lot.

Last edited by instarx; 11-13-2008 at 10:25 AM..
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